Plasma treatment of a semiconductor surface for enhanced nucleation of a metal-containing layer

ABSTRACT

A method for forming a dielectric layer is provided. The method may include providing a semiconductor surface and etching a thin layer of the semiconductor substrate to expose a surface of the semiconductor surface, wherein the exposed surface is hydrophobic. The method may further include treating the exposed surface of the semiconductor substrate with plasma to neutralize a hydrophobicity associated with the exposed surface, wherein the exposed surface is treated using plasma with a power in a range of 100 watts to 500 watts and for duration in a range of 1 to 60 seconds. The method may further include forming a metal-containing layer on a top surface of the plasma treated surface using an atomic layer deposition process.

CROSS REFERENCE TO RELATED APPLICATION(S)

The present application is a divisional of U.S. patent application Ser.No. 11/290,320, filed on Nov. 30, 2005 now U.S. Pat. No. 7,618,902 andentitled “PLASMA TREATMENT OF A SEMICONDUCTOR SURFACE FOR ENHANCEDNUCLEATION OF A METAL-CONTAINING LAYER,” the entirety of which isincorporated by reference herein.

FIELD OF THE INVENTION

The present invention relates generally to semiconductor processing, andmore particularly to plasma treatment of a semiconductor surface forenhanced nucleation of a metal-containing layer.

RELATED ART

Increasingly, semiconductor devices require thin SiO_(n) based gatedielectric films. Thin SiO_(n) based gate dielectric films, however,result in increased gate leakage. High dielectric constant (K) films arenow being considered as a replacement for the SiO_(n) based gatedielectric. Traditionally, high dielectric constant (K) films have beenformed using a process known as atomic layer deposition (ALD). Thin gatedielectric films formed using the ALD process, however, result in poornucleation of the high K dielectric on a silicon containing surface.Previous attempts to solve this problem have involved use of a standardclean (e.g., SC-2 clean). This step, however, deposits a thin layer ofchemical oxide on which the gate dielectric material deposited using theALD process nucleates. As a result, the chemical oxide becomes anintegral part of the gate dielectric affecting the integrity and scalingof the gate dielectric. Furthermore, the chemical oxide reduces theoverall dielectric constant of the gate dielectric film.

Thus, there is a need for methods for plasma treatment of asemiconductor surface for enhanced nucleation of a metal-containinglayer.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is illustrated by way of example and not limitedby the accompanying figures, in which like references indicate similarelements, and in which:

FIG. 1 is a cross section view of a semiconductor device duringprocessing, consistent with one embodiment of the invention;

FIG. 2 is a cross section view of a semiconductor device being treatedwith plasma, consistent with one embodiment of the invention;

FIG. 3 is a cross section view of a semiconductor device with a plasmamodified layer, consistent with one embodiment of the invention; and

FIG. 4 is a cross section view of a semiconductor device with a gatedielectric, consistent with one embodiment of the invention.

Skilled artisans appreciate that elements in the figures are illustratedfor simplicity and clarity and have not necessarily been drawn to scale.For example, the dimensions of some of the elements in the figures maybe exaggerated relative to other elements to help improve theunderstanding of the embodiments of the present invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

In one aspect, a method for forming a dielectric layer is provided. Themethod may include providing a semiconductor surface and etching a thinlayer of the semiconductor substrate to expose a surface of thesemiconductor surface, wherein the exposed surface is hydrophobic. Themethod may further include treating the exposed surface of thesemiconductor substrate with plasma to neutralize a hydrophobicityassociated with the exposed surface. The method may further includeforming a metal-containing layer on a top surface of the plasma treatedsurface using an atomic layer deposition process.

In another aspect, a method for forming a high constant dielectric layeris provided. The method may include etching a thin layer of asemiconductor substrate to expose a surface of the semiconductorsubstrate, wherein the exposed surface is hydrophobic. The method mayfurther include treating the exposed surface of the semiconductorsubstrate with plasma to neutralize a hydrophobicity associated with theexposed surface and to change a top layer of the semiconductor substrateinto an amorphous form. The method may further include forming ametal-containing layer on a top surface of the plasma treated surfaceusing an atomic layer deposition process.

FIG. 1 is a cross section view of a semiconductor device duringprocessing, consistent with one embodiment of the invention.Semiconductor device 100 may include a substrate 10. In one formsubstrate 10 may be a bulk semiconductor such as silicon, silicongermanium, or germanium, or any suitable semiconductor material.Alternatively, substrate 10 may be implemented as a silicon-on-insulator(SOI) substrate. As part of the first step, the top surface 12 ofsubstrate 10 may be etched to remove any oxide, for example, nativeoxide formed on top surface 12 of substrate 10. By way of example, layer14, which may be 10-20 Angstroms thick, may be etched away. Any suitableetching technique, such as dry etching or wet etching may be used. Byway of example, hydrofluoric acid may be used to etch layer 14. AlthoughFIG. 1 shows a bottom layer substrate 10 as being etched, a substratelike layer at another level of semiconductor device 100 may be etchedsimilarly, as well.

Next, as shown in FIG. 2, top surface 16 of semiconductor device 100 maybe subjected to a plasma treatment 18. Use of hydrofluoric acid may maketop surface 16 of substrate 10 hydrophobic. By way of example, anin-situ plasma treatment may be performed to neutralize hydrophobicsurface (e.g., top surface 16 of semiconductor device 100). Plasmatreatment 18 may be performed using power in a range of 100 watts to1000 watts. Plasma treatment 18 may be performed for a duration of 1second to 60 seconds. Any inert gas, such as Argon, Nitrogen, Helium,Xenon, or a combination thereof may be used as part of the plasmatreatment beyond the plasma ignition stage. As shown in FIG. 3, plasmatreatment may result in a plasma modified layer 20. Treating the exposedsurface of the semiconductor substrate with plasma may improve thenucleation of the metal-containing layer on a top surface 22 of plasmamodified layer 20. As a result of the plasma treatment, plasma modifiedlayer 20 may be changed into a more amorphous form. By way of example,plasma modified layer 20 may be 10-100 Angstroms deep. To further aid inthe process of changing plasma modified layer 20 into an amorphous form,additional gases such as, fluorine (e.g., NF₃, F₂, or B₃F₆,) chlorine(e.g., Cl₂), and/or nitrogen (N₂ or NH₃) may be used.

Next, as shown in FIG. 4, using an atomic layer deposition process, athin gate dielectric, such as a metal oxide may be deposited on a topsurface 22 of plasma modified layer 20. Thin gate dielectric layer(e.g., a metal-containing layer) may be formed using multiple cycles ofthe atomic layer deposition process. Each cycle may result in at least apartial metal oxide layer being formed on top surface 22 of plasmamodified layer 20. Using multiple atomic layer deposition cyclesdeposition fronts 24, 26, and 28 may result in formation of ametal-containing layer 30. By way of example, metal-containing layer 30may be any metal oxide layer, such as, for example, hafnium dioxide,lanthanum oxide, yttrium oxide, titanium oxide, tantalum oxide, or anoxide having other rare earth metals or transition metals. The metaloxide may also include any number of metals, such as, for example,hafnium aluminum oxide, other metal aluminates, etc. Alternatively,metal-containing layer 30 may be any metal silicate layer, such as, forexample, hafnium silicate, lanthanum silicate, and any other silicateshaving other rare earth metals or transition metals. Additionally and/oralternatively, metal-containing layer 30 may also includemetal-silicon-oxynitride, such as HfSi_(x)O_(y)N_(z).

In the foregoing specification, the invention has been described withreference to specific embodiments. However, one of ordinary skill in theart appreciates that various modifications and changes can be madewithout departing from the scope of the present invention as set forthin the claims below. Accordingly, the specification and figures are tobe regarded in an illustrative rather than a restrictive sense, and allsuch modifications are intended to be included within the scope ofpresent invention.

Benefits, other advantages, and solutions to problems have beendescribed above with regard to specific embodiments. However, thebenefits, advantages, solutions to problems, and any element(s) that maycause any benefit, advantage, or solution to occur or become morepronounced are not to be construed as a critical, required, or essentialfeature or element of any or all the claims. As used herein, the terms“comprises,” “comprising,” or any other variation thereof, are intendedto cover a non-exclusive inclusion, such that a process, method,article, or apparatus that comprises a list of elements does not includeonly those elements but may include other elements not expressly listedor inherent to such process, method, article, or apparatus.

1. A method for forming a dielectric layer, comprising: providing asemiconductor substrate; etching a thin layer of the semiconductorsubstrate to expose a surface of the semiconductor substrate; treatingthe exposed surface of the semiconductor substrate with plasma to form aplasma modified layer of an amorphous form between 10 to 100 Angstromsdeep; and forming a metal-containing dielectric layer on a top surfaceof the plasma treated surface using an atomic layer deposition process.2. The method of claim 1, wherein etching comprises using hydrofluoricacid to etch the thin layer.
 3. The method of claim 1, wherein theplasma is performed in situ.
 4. The method of claim 1, wherein themetal-containing dielectric layer comprises a metal oxide including atleast one of hafnium dioxide, lanthanum oxide, yttrium oxide, titaniumoxide, tantalum oxide, zirconium oxide, or an oxide having other rareearth metals or transition metals, or any combination thereof.
 5. Themethod of claim 4, wherein the metal-containing dielectric layer furthercomprises aluminates.
 6. The method of claim 1, wherein themetal-containing dielectric layer comprises at least one of metalsilicate and metal-silicon-oxynitride.
 7. The method of claim 6, whereinthe metal silicate is at least one of hafnium silicate, lanthanumsilicate, and any other silicates having other rare earth metals ortransition metals, or any combination thereof.
 8. The method of claim 1,wherein treating the exposed surface of the semiconductor substrate withplasma creates a plasma modified layer and improves the nucleation ofthe metal-containing dielectric layer on a top surface of the plasmamodified layer.
 9. The method of claim 1, wherein the exposed surface istreated using plasma with a power in a range of 100 watts to 500 wattsfor a duration in a range of 1 to 60 seconds.
 10. The method of claim 1,wherein treating the exposed surface of the semiconductor substrateincludes using a plasma including an inert gas.
 11. The method of claim10, wherein treating the exposed surface of the semiconductor substratewith plasma including the inert gas includes using the inert gas beyondthe plasma ignition stage.
 12. The method of claim 1, wherein treatingthe exposed surface of the semiconductor substrate with plasma to form aplasma modified layer comprises providing an additional gas including atleast one of fluorine, chlorine, and nitrogen.
 13. The method of claim1, wherein forming a metal-containing dielectric layer includes forminga thin gate dielectric layer on the top surface of the plasma treatedsurface.
 14. The method of claim 1, wherein forming a metal-containingdielectric layer comprises completing multiple cycles of the atomiclayer deposition process.
 15. The method of claim 1, wherein themetal-containing dielectric layer comprises hafnium dioxide.
 16. Themethod of claim 1, wherein etching a thin layer comprises removing anative oxide formed on a top surface of the semiconductor substrate. 17.The method of claim 1, wherein the plasma modified layer is betweenabout 11 and about 100 Angstroms deep.